Between 1948 and 1961, barges laden with industrial waste, including high concentrations of once-ubiquitous agricultural insecticide, Dichlorodiphenyltrichloroethane (DDT), were indiscriminately discharged into the Pacific Ocean.…

The post DDT is a Deep-Sea Toxic Time Capsule first appeared on Deep Sea News.

Hi,

reading Verilog®-A Language Reference I found this description of ddt function I don't understand:

Use the time derivative operator to calculate the time derivative of an argument.

ddt( input [ , abstol | nature ] )

input is a dynamic expression.

abstol is a constant specifying the absolute tolerance that applies to the output of the ddt operator. Set abstol at the largest signal level that you consider negligible.

nature is a nature from which the absolute tolerance is to be derived.

Can anyone explain how abstol and nature are defined? how using them? an example would be really appreciated.

Thanks

Andrea

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